Chafuroside is a flavone C-glycoside which is one of flavone derivatives, and is known to exhibit properties such as antioxidant, antiallergic, anti-inflammatory and carcinogenesis inhibiting activities. It is known that chafuroside is a compound isolated from oolong tea, and its structural formula has been determined.
Uehara et al. carried out a test wherein atopic patients drunk every half amount of 400 ml of a thick solution condensed twice of commercially available oolong tea after breakfast and supper everyday for 4 weeks, and it was investigated whether daily dermal inflammation and intense itching accompanied thereby which were inherent to the patients could be prevented effectively or not, and had found that said oolong tea was effective in 62% of atopic patients who participated in this test (see Non-patent Document 1).
On the basis of the above-mentioned knowledge, Kasuya et al. tried to isolate effective ingredients from said oolong tea by using an effectiveness for an atopic disease model induced by 2,4-dinitro-fluorobenzene as an index for isolation. As a result, approximately 1 mg each of two ingredients exhibiting activities via oral administration was obtained from approximately 3.5 kg of tea leaves of the oolong tea, and structural formulas thereof were determined. Since they were novel compounds, they were given a name as “chafuroside A” and “chafuroside B” respectively (see Patent Document 1).
According to the above document, chafurosides A and B can be represented by the following formulas as A2-2 and B2-2 respectively:

Subsequently, detailed studies were made on biological activities of chafurosides A and B. It was shown that, in an atopic disease model induced by 2,4-dinitro-fluorobenzene, chafuroside A exhibited a significant dermal inflammation-inhibiting activity at 10 μg/kg, which was comparable with a commercially available steroid anti-inflammatory agents “Prednisolone” (10 mg/kg) and “Betamethasone” (0.8 mg/kg) at a lower dosage (see Patent Document 1 and Patent Document 2).
In addition, it was confirmed that chafuroside A exhibited an effectively-inhibiting activity at 2.5 mg/kg which was a same dosage as indomethacin against intestinal polyp formation induced by azoxymethane (AOM) in a rat large bowel of a Min mouse. And it was assumed that this effect was caused by inhibitory action of chafuroside A to COX-2. In view of these results and the structure thereof, chafuroside A has a high probability of becoming a new type of anti-inflammatory agents (see Patent Document 2, Non-patent Document 3).
As mentioned above, chafurosides A and B exhibit more excellent biological activities than a steroid anti-inflammatory agent which is one of the most useful medicines at present and its usefulness is expected, and so, various methods for industrially producing them had been studied in the past.
For example, it was made an attempt to synthesize them from well-known flavone C-glycosides “isovitexin” and “vitexin” respectively. Among them, synthesis of chafurosides A and B from isovitexin and vitexin using Mitsunobu reaction represented by the following chemical reaction formula was proposed (Patent Document 2). However, since an azo reagent having high risk of explosion is used in this method, its industrialization is extremely difficult.

Although a novel chemical synthesizing method of chafuroside A is also disclosed in the above-mentioned Non-patent Document 2, the method has a defect of poor safety (see Patent Document 3, Patent document 4 and Non-patent Document 2).
In view of the structures, producing methods and biological activities of chafurosides A and B as mentioned above, production mechanism of chafurosides A and B in oolong tea leaves is very interesting. However, an industrial production method thereof which is simple in good yield, safe and inexpensive has not been established. In view of high usefulness of these compounds, it is strongly desired to develop an effective production method thereof.